Crema is the initial light/tawny colored liquid that comes out during an espresso extraction. It is what causes that 'Guinness effect' that folks sometimes reference. As the lighter liquid infuses with the darker liquid that comes after, it filters up and 'settles', leaving a tan colored layer on top of the darker espresso below.
The formation of crema is a blend of a few different things: As water is forced through the coffee under pressure, it emulsifies the natural fat/oil content in the bean, suspending it in tiny microbubbles of air. Additionally, after coffee is roasted, it out-gases C02 for awhile (generally for the next 24 - 72 hours post-roast) and so coffee that was more freshly roasted will also emit some C02 during extraction.
I will try this with other coffees to see if this issue can be remedied.
Many will say that the crema is not a big deal, but I have definitely noticed a better cup of coffee when it *is* there.
This issue aside, this is a handy little espresso maker, and it has the option of choosing a two or four-cup brew, as well as a double-tasking scoop/tamper. The included instructions are easy to follow, and a two-cup brew is done in less than two minutes!
You can buy it here: